Institute of Molecular Medicine, Department of Life Science, National Tsing Hua University, Hsinchu, Taiwan 30034, Republic of China.
Development. 2011 Sep;138(17):3803-12. doi: 10.1242/dev.062257. Epub 2011 Jul 27.
Cell sorting involves the segregation of two cell populations into `immiscible' adjacent tissues with smooth borders. Echinoid (Ed), a nectin ortholog, is an adherens junction protein in Drosophila, and cells mutant for ed sort out from the surrounding wild-type cells. However, it remains unknown which factors trigger cell sorting. Here, we dissect the sequence of this process and find that cell sorting occurs when differential expression of Ed triggers the assembly of actomyosin cable. Conversely, Ed-mediated cell sorting can be rescued by recruitment of Ed, via homophilic or heterophilic interactions, to the wild-type cell side of the clonal interface, even when differential Ed expression persists. We found, unexpectedly, that when actomyosin cable was largely absent, differential adhesion was sufficient to cause limited cell segregation but with a jagged tissue border (imperfect sorting). We propose that Ed-mediated cell sorting is driven both by differential Ed adhesion that induces cell segregation with a jagged border and by actomyosin cable assembly at the interface that smoothens this border.
细胞分选涉及将两个细胞群体分离到具有平滑边界的“不可混溶”相邻组织中。粘蛋白同源物 Echinoid（Ed）是果蝇中的一个黏着连接蛋白，ed 突变体从周围的野生型细胞中分离出来。然而，触发细胞分选的因素仍不清楚。在这里，我们剖析了这个过程的顺序，发现当 Ed 的差异表达触发肌动球蛋白电缆的组装时，细胞分选就会发生。相反，即使 Ed 的差异表达持续存在，通过同种或异种相互作用将 Ed 募集到克隆界面的野生型细胞侧，也可以挽救 Ed 介导的细胞分选。出乎意料的是，我们发现，当肌动球蛋白电缆大量缺失时，差异粘附足以导致有限的细胞分离，但组织边界参差不齐（不完全分选）。我们提出，Ed 介导的细胞分选既由诱导具有锯齿状边界的细胞分离的 Ed 差异粘附驱动，也由界面处的肌动球蛋白电缆组装驱动，该组装使边界变平滑。
